Difference Between Prokaryotic Cell and Eukaryotic Cell

All living things are made up of cells, the basic units of life. There are two main types of cells: Prokaryotic cells and Eukaryotic cells.

Prokaryotic Cell

  • Definition: A prokaryotic cell is a simple, small cell without a nucleus or membrane-bound organelles. Found in bacteria and archaea, it has a nucleoid region containing DNA, a cell wall, a plasma membrane, ribosomes, and sometimes a capsule and flagella.
  • Examples: Bacteria and archaea.
  • Characteristics:
    • No Nucleus: The genetic material (DNA) is not enclosed in a nucleus. It is found in a region called the nucleoid.
    • Simple Structure: Lacks membrane-bound organelles like mitochondria or chloroplasts.
    • Cell Wall: Most prokaryotic cells have a cell wall that provides shape and protection.
    • Reproduction: Reproduces mainly through binary fission, a simple form of cell division.

Prokaryotic Cell Diagram

Prokaryotic Cell 1

This diagram shows the structure of a prokaryotic cell, specifically a bacterial cell. The labeled parts include the following:

  • Capsule: The outermost layer is a protective coating found in some bacteria. It helps protect the cell from dehydration and phagocytosis (engulfment by other cells) and aids in surface attachment.
  • Cell Wall: A rigid layer just inside the capsule. It provides structural support and shape to the cell. In bacteria, it is made up of peptidoglycan.
  • Plasma Membrane: A flexible lipid bilayer located just beneath the cell wall. It controls the movement of substances in and out of the cell, thus maintaining the internal environment.
  • Cytoplasm: The gel-like substance filling the inside of the cell. It contains all the cell’s internal components and is the site where many metabolic reactions occur.
  • DNA (Nucleoid): The region in the cell where the circular DNA molecule is located. It contains the genetic material of the cell, which controls all cellular activities and replication.
  • Ribosomes: Small structures scattered throughout the cytoplasm. They are the sites of protein synthesis where genetic information is translated into proteins.
  • Mesosome: Folded extensions of the plasma membrane. They are believed to be involved in cell division and distribution of DNA to daughter cells, and also play a role in respiration and increasing the surface area for enzyme attachment.
  • Bacterial Flagellum: A long, whip-like structure extending from the cell surface. It provides motility to the bacterial cell, allowing it to move towards favorable environments and away from harmful ones.

Eukaryotic Cell

  • Definition: A eukaryotic cell is a complex, larger cell with a nucleus and membrane-bound organelles. Found in plants, animals, fungi, and protists, it includes organelles like mitochondria, endoplasmic reticulum, Golgi apparatus, and, in plants, chloroplasts, along with a well-defined nucleus.
  • Examples: Plants, animals, fungi, and protists.
  • Characteristics:
    • Nucleus: Contains the genetic material (DNA) enclosed within a nuclear membrane.
    • Complex Structure: Has various membrane-bound organelles like mitochondria, endoplasmic reticulum, Golgi apparatus, and, in plant cells, chloroplasts.
    • Cell Wall: Plant cells and fungi have a cell wall; animal cells do not.
    • Reproduction: Reproduces through mitosis (for growth and maintenance) and meiosis (for sexual reproduction).

Eukaryotic Cell Diagram

Eukaryotic Cell Diagram

Eukaryotic cells are more complex than prokaryotic cells and have membrane-bound organelles that perform specific functions. Here are the parts labeled in the diagram:

  • Nucleus: The nucleus is the central organelle of the cell and contains the genetic material (DNA) that instructs the cell on how to function and reproduce. The nucleus is surrounded by a nuclear membrane, which separates it from the cytoplasm.
  • Nucleolus: The nucleolus is a region inside the nucleus that is responsible for producing ribosomes.
  • Ribosomes: Ribosomes are small organelles that are responsible for protein synthesis. They are found throughout the cytoplasm and on the rough endoplasmic reticulum.
  • Golgi apparatus (Golgi bodies): The Golgi apparatus is an organelle that packages, modifies, and transports materials throughout the cell.
  • Plasma membrane: The plasma membrane is the outer boundary of the cell and controls what enters and leaves the cell.
  • Cytoplasm: The cytoplasm is the jelly-like substance that fills the cell and contains all of the cell’s organelles except for the nucleus.
  • Endoplasmic reticulum (ER): The endoplasmic reticulum is a network of membranes that is involved in protein synthesis, lipid synthesis, and detoxification. There are two types of ER: rough ER and smooth ER. Rough ER has ribosomes attached to its surface, while smooth ER does not.
  • Mitochondria: Mitochondria are known as the powerhouse of the cell. They are responsible for cellular respiration, which is the process of converting glucose into energy.
  • Vacuoles: Vacuoles are storage sacs that can store water, nutrients, and waste products.
  • Centrioles: Centrioles are organelles that help with cell division. They are located near the nucleus.

Difference Between Prokaryotic and Eukaryotic Cell

FeatureProkaryotic CellEukaryotic Cell
NucleusNo nucleusHas a nucleus
SizeSmaller (1-10 micrometers)Larger (10-100 micrometers)
ComplexitySimple structureComplex structure
DNACircular, found in nucleoidLinear, enclosed in a nucleus
OrganellesNo membrane-bound organellesContains membrane-bound organelles
Cell DivisionBinary fissionMitosis and meiosis
Cell WallPresent (contains peptidoglycan in bacteria)Present in plants and fungi (contains cellulose in plants and chitin in fungi); absent in animal cells
RibosomesSmaller (70S)Larger (80S)
CytoskeletonAbsent or very simplePresent and complex
ExamplesBacteria, ArchaeaPlants, Animals, Fungi, Protists
ReproductionAsexual reproduction only (binary fission)Both asexual (mitosis) and sexual (meiosis) reproduction
FlagellaSimple, composed of flagellinComplex, composed of microtubules
10 key differences between prokaryotic and eukaryotic cells:

Key Differences

  • Nucleus: Prokaryotic cells lack a nucleus; eukaryotic cells have a nucleus.
  • Size: Prokaryotic cells are generally smaller (1-10 micrometers) than eukaryotic cells (10-100 micrometers).
  • Organelles: Prokaryotic cells do not have membrane-bound organelles; eukaryotic cells do.
  • DNA Structure: Prokaryotic DNA is circular and not associated with histones(a protein that provides structural support for a chromosome); eukaryotic DNA is linear and associated with histones.